In general, a three-dimensional image processing system has various areas of application. In particular, the three-dimensional image processing system is frequently used for designing and constructing three-dimensional structures such as automobiles and ships, and visualizing three-dimensional volume data in medical imaging applications. In medical imaging applications, the volume data comes in a series of two-dimensional images obtained from computed tomography (CT) or magnetic resonance imaging (MRI).
With the use of only two-dimensional images, it is difficult to obtain an entire three-dimensional effect, and it is impossible to observe an arbitrary section. On the other hand, with three-dimensional medical imaging technology it is possible to search the correct position of an affected area and establish proper surgical plans.
When a user tries to look at an arbitrary internal organ in a three-dimensional medical image, it is difficult to look at the desired organ because other organs obscure it. At this time, if a volume of interest (VOI) is specified in three-dimension and a corresponding volume region is rendered, it is not necessary to perform segmentation in two-dimensional images before three-dimensional rendering as in conventional technologies.
Therefore, in medical applications, the VOI is very helpful in diagnoses and relieves doctors and radiologists from performing manual tasks. Slab rendering is the rendering of an arbitrary partial region in the three-dimensional volume data in order to support the VOI.
A conventional VOI rendering system has a problem in that an interface for—expressing an interested region is too complicated to be used by non-trained users such that the planes for the VOI are specified respectively and grouped in order to designate a slab.
Also, the conventional system rotates a reference image while moving a mouse on a plane. In this case, only the rotations on the basis of two coordinate axes are available.
For example, when the mouse is horizontally moved, the reference image is rotated using a vertical axis on a screen as a rotation axis. When the mouse is vertically moved, the reference image is rotated using a horizontal axis on the screen as the rotation axis. Therefore, it is difficult to intuitively view and manipulate the displayed slab. Also, it has limitation in displaying the interested region because it designates the slab to be parallel to the respective axes.